Method and System of Leveraging Onboard Positive Train Control Equipment

ABSTRACT

A system of a leading locomotive with a reduced complement of onboard Positive Train Control (PTC) equipment leveraging a full complement of PTC equipment in a trailing locomotive, while operating in a PTC territory. The system can be applied to a push-pull passenger train, wherein the cab car has the reduced complement of onboard PTC equipment and the locomotive has the full complement, whereby the train is operable in both directions in a PTC territory. The system can also serve as an expedient repair of a leading locomotive with failed onboard PTC equipment by leveraging the functional PTC equipment in another locomotive in the consist. The same leveraging principle can allow a PTC-equipped locomotive to operate in a non-interoperable PTC territory. Considerable cost savings are achieved compared to the prior art practice of fully equipping all locomotives and cab cars with a full PTC installation.

RELATED U.S. APPLICATION DATA

This application claims the benefit of Provisional Patent Application No. 62/646,898, entitled “Method and System of Leveraging Onboard Positive Train Control Equipment” filed Mar. 22, 2018, by the present inventor and which is incorporated herein by reference in its entirety.

BACKGROUND—PRIOR ART Prior Art—Cost Considerations

The Rail Safety and Improvement Act of 2008, the Positive Train Control Enforcement and Implementation Act of 2015, and ensuing regulations in 49 CFR 236, Subpart I, mandated most railroads in the U.S. to implement a comprehensive train control system known as Positive Train Control (PTC) and to install onboard PTC equipment upon nearly 20,000 locomotives and unpowered passenger cab cars in their fleets. The 2008 act created an unfunded mandate for railroads to invest as much as $22 billion in a complex, extensive infrastructure that had to be developed from a fragmented collection of relatively primitive train control systems. The mandate has been especially burdensome to cash-strapped commuter railroads and small, short line railroads. The 2008 act established a completion target of Dec. 15, 2015. Funding constraints, issues of technological readiness, radio spectrum constraints, and the sheer volume of work to develop, manufacture, install, and commission the system put the target out of reach. The 2015 act extended the deadline to Dec. 31, 2018, with a further extension to Dec. 31, 2020, to be made on a case-by-case basis, if substantial progress toward implementation had been made. As of Dec. 31, 2018, the Federal Railway Administration (FRA) reported that the railroads had retrofitted onboard PTC equipment onto essentially all their locomotives and cab cars that travel in PTC territories. Nevertheless, the railroads will make further investments in onboard equipment as they place new locomotives and cab cars into service, and as the installed equipment fails or becomes outdated. The high cost of retrofitting PTC onto older locomotives or low-utilization locomotives may not be justified, rendering them as stranded assets, even though they may be otherwise useful as standby or helper locomotives in PTC territories.

Prior Art—Failures

PTC has been subject to occasional failures on various levels. It is instructive that the word “failure” appears no fewer than 161 times in 49 CFR 236, Subpart I. Section 236.1029 gives detailed procedures in the event of an en-route failure, particularly the failure of onboard equipment. In many cases, the regulations require the train to operate at restricted speed, disrupting its own schedule and the schedules of other rail traffic in the area. It may be possible to rearrange the locomotive consist to move a unit with failed equipment out of the controlling position, but this can also delay the train, and a proximate siding or turnout is required. Section 236.1029(b)(6) states that a train with failed onboard PTC equipment may continue no farther than the next forward designated location for the repair or exchange of the equipment. Not only are on-road failures disruptive and costly, but they compromise the safety of the affected train and potentially of rail work crews and other rail traffic in the vicinity.

Prior Art—Interoperability Issues

Interoperability is the area where PTC progress is most lagging. FRA reported that, as of Dec. 31, 2018, only 16% of required tenant railroads had achieved interoperability with their host railroads' PTC systems. There are four principal PTC systems in use in the U.S.:

-   -   1. I-ETMS® (Interoperable—Electronic Train Management System) is         a product of Wabtec Corporation and is the most widely system in         the U.S.     -   2. ACSES (Advanced Civil Speed Enforcement System) is a product         of Alstom and in use by Amtrak and other railroads on the         Northeast corridor.     -   3. ITCS (Incremental Train Control System) is a sole-sourced         product of Alstom and is in use in the upper Midwest by Amtrak.     -   4. E-ATC (Enhanced Automatic Train Control) is a low-cost system         based on legacy automatic train control, upgraded to conform to         PTC requirements. It is used by smaller commuter railroads and         is the only system of the four not to use the 220 MHz PTC radio         band.

None of the four systems listed above are interoperable fully, if at all. Lack of interoperability may arise from a host of issues, from fundamentally different system architectures to incompatible radio spectra. This can be a constraint upon the common practice of freight railroads leasing locomotives from other railroads. If the lessor and lessee have different PTC systems, the non-interoperable locomotive will be restricted to a trailing position in the consist, or compatible onboard PTC equipment will have to be retrofitted at considerable cost.

Prior Art—Push-Pull Passenger Trains

Push-pull passenger trains operate in both directions, with a locomotive in the controlling position in pull mode and an unpowered cab car in the controlling position in push mode. The practice to date has been to duplicate a full onboard PTC installation in both the locomotive and the cab car. Equipping only the locomotive would require turning the train at each end of the line, defeating the purpose of a push-pull train: Most push-pull trains are operated by commuter railroads that have very limited capital resources. For example, the Rail Runner Express commuter line in New Mexico, which has nine trains, is facing a cost of $55 to $60 million to implement PTC, more than 25 times its annual fare receipts of $2.15 million.

DETAILED DISCUSSION Advantages

Under 49 USC 236, Subpart I, a train operating in a Positive Train Control (PTC) territory must be disposed with a full complement of onboard PTC equipment. This led railroads to the practice of fully equipping all their locomotives that operate in PTC territories. The disclosed embodiments have the following advantages:

-   1) Cost Savings: A PTC remote locomotive 16, as disclosed, can     operate in the leading position in a PTC territory by leveraging the     resources of a PTC host locomotive 18 elsewhere in the consist. The     scope and cost of equipping a two-unit locomotive consist or a     locomotive-cab car pair with PTC according to the disclosed     embodiments is about one-half of equipping both with PTC according     to the prior art. Beyond the capital cost savings, the railroad     would save one half of the recurring cost of subscriptions for a     220-MHz PTC data radio. -   2) Stranded Assets: The cost of retrofitting full PTC onto older and     low-utilization locomotives may not be justified, rendering them as     stranded assets. In contrast, the low cost of the disclosed     embodiments may justify retrofitting these locomotives, extending     their economic lives. -   3) Operations: The disclosed leveraging principle can provide     railroads more flexibility by equipping a helper or standby     locomotive as a remote locomotive 16 and coupling it into the     leading position of a consist. Rearranging locomotive consists to     position a PTC-equipped locomotive in the leading position requires     time and effort and suitable track arrangements. -   4) PTC Failures: A disclosed embodiment applies the leveraging     principle to quickly rescue a leading locomotive which has an     on-road failure of onboard PTC, eliminating the disruption of     rearranging the locomotive consist, replacing or repairing the     failed equipment, or operating under onerous speed restrictions. -   5) Interoperability: As noted in the prior art discussion, the     several PTC systems in use across the U.S. are generally not     interoperable. As shown in FIG. 9, Case G, a disclosed embodiment     allows a non-interoperable locomotive to operate as a leading     locomotive, as long as a locomotive in the consist is interoperable     with the local PTC environment. This can broaden the pool of leased     locomotives available to a lessor, even though they may not be     interoperable with the local PTC environment.

THE DRAWINGS

In the following discussion, reference numerals less than 20 refer to rail vehicles. Reference numerals 24 and greater, but less than 50, apply to elements within rail vehicles without PTC onboard equipment installed, according to the prior art. Reference numerals 50 and greater, but less than 100, apply to elements that comprise onboard PTC equipment, according to the prior art. Reference numerals 100 and greater apply to elements that comprise PTC onboard equipment, according to the embodiments disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic of elements of a locomotive without Positive Train Control (PTC) according to the prior art.

FIG. 1B is a schematic of an automatic brake valve that is cut out according to the prior art.

FIG. 2 is a schematic of a locomotive disposed with a full complement of onboard PTC according to the prior art.

FIG. 3 is a schematic of a first embodiment of a System of Leveraging Onboard Positive Train Control Equipment.

FIG. 4 is a schematic of ant alternative embodiment that employs a Remote Terminal to aggregate signals and data and exchange with the onboard computer by means of a wired or wireless data connection.

FIG. 5A is a flowchart of a PTC penalty brake application according to the prior art.

FIG. 5B is a flowchart of a PTC emergency brake application according to the prior art.

FIG. 6 is a flowchart of a PTC penalty brake application by all disclosed embodiments.

FIG. 7 is a flowchart of a PTC emergency brake application by all disclosed embodiments.

FIG. 8 is a diagram of examples of locomotive consists, including some examples according to the prior art.

FIG. 9 is a diagram of further examples of locomotive consists, including one example according to the prior art.

DETAILED DISCUSSION—FIG. 1A AND 1B

FIG. 1A is a schematic of elements of a locomotive 14 without onboard Positive Train Control (PTC) equipment according to the prior art. The elements shown relate to both the prior art and to the disclosures herein. A train is composed of one or a plurality of locomotives that provide motive power to the train, and one or a plurality of unpowered railcars. To provide the motive power required by a typical train, a railroad will often assemble a locomotive consist of two or more coupled locomotives. Front coupler 36 and rear coupler 38 couple locomotive 14 to other locomotives or to railcars. The leading locomotive of a consist is also the controlling locomotive, which has operative control of the train. The one or more locomotives behind it are referred to as trailing locomotives. A pneumatic brake pipe 28 runs through the length of a train and has two functions: to distribute compressed air for braking to each railcar in the train, and to signal each railcar to apply or release its brakes by means of pressure changes in the brake pipe 28.

Each locomotive 14 in the train has an automatic brake valve (ABV) 26 with a connection to the brake pipe 28. When running, the ABV 26 in the controlling locomotive regulates the pressure in the brake pipe 28 at nominal values, typically 90 pounds per square inch (PSI) for freight trains and 110 PSI for passenger trains. Reducing the pressure in the brake pipe 28 results in a coordinated application of the brakes throughout the train. To make a service brake application, the ABV 26 in the controlling locomotive reduces the pressure in the brake pipe 28 at a measured, service rate. The braking effort is roughly proportional to the pressure reduction, up to a limit known as full-service braking which corresponds to a reduction of about 20 PSI. A further reduction produces no further braking effort, provided it occurs at the service rate. Braking effort in excess of full-service may be obtained by making an emergency brake application which vents the brake pipe 28 rapidly and completely. Only the ABV 26 in the controlling locomotive may connected to the brake pipe 28. Every other ABV 26 must be isolated, or it will charge the brake pipe 28 when a service reduction is attempted in the controlling locomotive, thereby counteracting the reduction and rendering the air brakes inoperable. Setting the MU valve 24 to the “lead” or “cut-in” position as shown schematically in FIG. 1A will connect ABV 26 to the brake pipe 28. In every trailing locomotive in the consist, the MU valve 24 must be set to the “trail” or “cut-out” position, as shown schematically in FIG. 1B, thereby isolating the ABV 26 from the brake pipe 28.

A Multiple Unit, or MU, trainline 34 runs the length of the consist and operatively connects all locomotives in the consist. Operating controls 32 in the controlling locomotive impose electrical control signals on specific wires in the trainline 34, coordinating the application of power, the application of dynamic braking, and the direction of movement.

A pressure switch, known synonymously as a Power Cut-out Switch, a Pneumatic Control Switch, or PCS 30, and operating controls 32 are features of every locomotive and are related to PTC functionality.

DETAILED DISCUSSION—FIG. 2

FIG. 2 is a schematic of a locomotive 14 disposed with a full complement of onboard PTC equipment according to the prior art. PTC consists of three major segments, operatively and continuously connected by wired or wireless communications: an office segment comprising principally a remote server and central database; a wayside segment comprising principally track signaling systems, track monitoring systems and track sensors; and, an onboard segment. The onboard segment comprises PTC equipment installed within a locomotive or cab car. The heart of the onboard segment is an onboard computer 50 that collects data through a plurality of signal and data input and output (I/O) ports, including:

-   -   a) Geo-location data from a GPS receiver 66 equipped with a GPS         antenna 68     -   b) Data from two-way radios 70, which operate in 220-MHz PTC         band, the cellular band, the IEEE 802.11 Wi-Fi band, and         possibly other bands, each receiving and transmitting through         antennas depicted collectively as two-way radio antenna 72.     -   c) Signals from the operating controls 32     -   d) Signals from the MU trainline 34     -   e) Signals representing the pressure in the brake pipe 28     -   f) Signals from a speed sensor 78 which receives and interprets         pulse signals from an axle speed generator 76     -   g) A signal indicating whether the PCS 30 is opened or closed,         the signal being sent through a PCS connection 74     -   h) A signal from a pressure switch 82 indicating whether the ABV         26 is cut in or isolated, the signal being sent through pressure         switch connection 84.

The onboard computer 50 writes operational data to a PTC event recorder 80, which records the data for logging and for forensic purposes. In addition, the onboard computer 50 transmits video signals though connection 62 to a cab display 60 that presents train status, including warnings of train control actions, to the engineer. Optionally, an audible alert 64 will sound with a visual warning. During a warning period, the engineer may take preemptive action to slow or stop the train by applying braking, removing traction power, or both, thereby avoiding a PTC enforcement. In the event the PTC system determines that a hazard on the track ahead requires immediate enforcement action, it will make the appropriate brake application without a warning.

PTC employs a braking algorithm to predict when a brake application must be initiated to stop the train short of a hazard identified on the tracks ahead. To precisely determine the position of the train, the onboard computer is configured with the offset distance, DIM. “G”, from the GPS antenna to the front coupler 36. The position of the rear coupler 38 is similarly relevant when the locomotive is operating in reverse. Dim “K” is the distance between the front coupler 36 and rear coupler 38.

PTC enforcement defaults to a penalty brake application which has the following characteristics: the pressure reduction is made at the service rate; the reduction is large enough to make a full-service brake application; the reduction retains enough pressure in the brake pipe 28 to make a subsequent emergency brake application; and, the application cannot be cancelled by the engineer. The onboard computer 50 initiates a penalty application by opening penalty solenoid valve 52 through penalty solenoid valve connection 54.

During braking, PTC will constantly and precisely monitor the position and speed of the train. If the PTC algorithm determines that the penalty application is insufficient to stop the train short of the hazard, then the onboard computer 50 will initiate an emergency brake application by energizing through connection 58 a large-capacity, emergency solenoid valve 56 that is directly connected to the brake pipe 28, venting the pressure contained therein quickly and completely.

The PCS 30 opens whenever PTC initiates a brake application. The opening of the PCS 30 unlatches a relay in the operating controls 32 that de-energize the throttle and generator field control wires in the MU trainline 34. This causes the engine in every locomotive in the consist to drop to idle speed and removes all traction power. PTC-initiated penalty and emergency brake applications differ in the following salient ways:

-   -   a) A PTC-initiated penalty application must be made through the         penalty solenoid valve 52 that acts upon the ABV 26 that is cut         in.     -   b) A PTC-initiated penalty application will open only the PCS 30         associated with that ABV 26, in the controlling locomotive,         thereby removing traction power through the MU trainline 34, as         described.     -   c) A PTC-initiated emergency application may be initiated by an         emergency solenoid valve 56 located in any locomotive or cab car         along the brake pipe 28.     -   d) A PTC-initiated emergency application will open the PCS 30 in         every locomotive in the consist.

DETAILED DISCUSSION—FIG. 3—A FIRST EMBODIMENT

FIG. 3 shows a First Embodiment of a System of Leveraging Onboard Positive Train Control Equipment according to claim 1. It is useful at this point to define the terms “remote locomotive” 16 and “host locomotive” 18 as they relate to the disclosed embodiments. A host locomotive 18, shown in partial view, hosts a full complement of onboard PTC equipment as shown schematically in FIG. 2. A remote locomotive 16 is equipped with a minimum complement of PTC equipment such that it can operate in the leading position in a PTC territory by leveraging the resources of the host locomotive 18 operating in a trailing position in the consist.

Regulations in 49 CFR 236.1006 state that “onboard PTC apparatus may be distributed among multiple locomotives . . . ”, and further state that “The controlling locomotive shall be equipped with a fully operative interface . . . ”. This requirement may be satisfied by installing a remote cab display 100 in the remote locomotive and a cab display data link 104 to the onboard computer 50. As described in the foregoing discussion, the ABV 26 in the host locomotive 18, in the trailing position must be cut out. This disables the penalty application function there, requiring the installation of a remote penalty solenoid valve 106 in the remote locomotive 16. A penalty signal link 108 operatively connects remote penalty solenoid valve 106 to the onboard computer 50.

In many PTC systems, the onboard computer 50 monitors the status of the operative PCS 30 and ABV 26, both of which are now located in the remote locomotive 16. A first auxiliary signal link 114 operatively connects the PCS 30 in the remote locomotive to the onboard computer 50. A remote pressure switch 110 is installed to monitor the status of ABV 26 in the remote locomotive 16. A second auxiliary signal link 112 operatively connects the remote pressure switch 110 in the remote locomotive to the onboard computer 50: Claims 2 and 3 pertain to the features in this paragraph.

When the remote locomotive 16 is coupled to the front of the train, distance DIM. “G” from the GPS antenna 68 in the host locomotive 18 to the front coupler of the remote locomotive 16 will increase by the length over its couplers DIM “K”. The onboard computer 50 will be configured with the total of DIM “G” and DIM “K” which is DIM “T”.

Comparing the full complement of onboard PTC equipment shown in FIG. 2, the savings in the cost and scope of equipment associated with the first embodiment in FIG. 3 are apparent. CL DETAILED DISCUSSION—FIG. 4—AN ALTERNATIVE EMBODIMENT

FIG. 4 is a schematic diagram of an alternative embodiment according to claim 4. It differs from FIG. 3 in the manner in which the remote locomotive 16 and host locomotive 18 are operatively connected. In FIG. 4 introduces a remote terminal 116 with a plurality of input-output (I/O) and data ports 118 and an aggregated data link 120 to onboard computer 50. The aggregated data link may be wired or wireless.

The remote cab display 100 connects to the I/O and data ports 118 through cab display data link 104. The remote penalty magnet valve 106 connects to the I/O and data ports 118 through a penalty signal link 108. The PCS 30 connects to the I/O and data ports 118 through a first auxiliary signal link 114. The remote pressure switch 110 connects to the I/O and data ports through a second auxiliary signal link 112. The remote terminal encodes and decodes data and signals and manages communications with the onboard computer through the aggregated data link 120.

The configurations of the remote locomotive 16 in FIGS. 3 and 4 can also apply to a cab car in a push-pull passenger train as described in claim 5.

DETAILED DISCUSSION—FIG. 5A—FLOWCHART OF PTC PENALTY BRAKE APPLICATION ACCORDING TO THE PRIOR ART

FIG. 5A is a flowchart showing the steps by which PTC carries out a penalty brake application according to the prior art. PTC initiates each process by identifying a hazard on the tracks ahead that requires enforcement. The process occurs entirely with the controlling locomotive, except: (1) the penalty application of brakes is propagated throughout the train by the brake pipe 28, and (2) the removal of the traction power is coordinated through the locomotive consist by the MU trainline 34.

DETAILED DISCUSSION—FIG. 5B—FLOWCHART OF PTC EMERGENCY BRAKE APPLICATION ACCORDING TO THE PRIOR ART

FIG. 5B is a flowchart showing the steps by which PTC carries out an emergency brake application according to the prior art. PTC initiates each process by identifying a hazard on the tracks ahead that requires enforcement. The processes in FIGS. 5A and 5B differ in how the pressure reduction in the brake pipe is made, and the amount of the reduction. Note that the penalty application in FIG. 5A only opens the PCS 30 in the controlling locomotive, whereas the emergency application in FIG. 5B opens the PCS 30 in all the locomotives.

DETAILED DISCUSSION—FIG. 6—FLOWCHART OF PTC PENALTY BRAKE APPLICATION ACCORDING TO THE DISCLOSED EMBODIMENTS

The flowchart in FIG. 6 is a flowchart showing the process steps whereby the onboard computer 50 in the host locomotive 18 initiates a penalty brake application in the remote locomotive 16. Comparing FIGS. 5A and 6 shows how the enforcement functions of braking and power removal are moved to the remote locomotive 16.

DETAILED DISCUSSION—FIG. 7—FLOWCHART OF PTC EMERGENCY BRAKE APPLICATION ACCORDING TO THE DISCLOSED EMBODIMENTS

The flowchart in FIG. 7 differs from that in FIG. 6 in that the braking enforcement function, an emergency braking application, remains in the host locomotive 18. As noted, an emergency braking application causes every PCS 30 in the locomotive consist to open, including the PCS 30 in the remote locomotive 16. It is this PCS 30 opening that causes power to be removed through the MU trainline 34.

DETAILED DISCUSSION—FIGS. 8 AND 9

FIG. 8—Examples of Locomotive Consists (Including Prior Art)—

FIG. 8 is a diagram showing various locomotive consists, both according to the prior art, and incorporating the embodiments disclosed in ways that reduce the scope of PTC equipment required for legal operation in a PTC territory. Comparing Cases A, B, and C, it is evident that the embodiment in Case C provides the operational flexibility of Case B, allowing movement of the consist in both directions without having to turn the consist. It is possible that the distance from the front coupler of a train to the GPS antenna 68 in the host locomotive 18 exceeds the configuration limit of a particular PTC system. This is especially true for push-pull passenger trains that may be several hundred feet long. Case D shows a solution that places a remote GPS receiver proximate to the front coupler of the remote locomotive or the cab car.

FIG. 9—Further Examples of Consists (Including Prior Art)

FIG. 9 shows various locomotive consists that include a locomotive equipped with PTC that is non-interoperable in the territory being travelled, and also a locomotive with failed onboard PTC. Case F depicts an embodiment that pertains to a locomotive that is non-interoperable with the local PTC environment. Case G depicts the embodiment that pertains to rescuing a locomotive with failed PTC onboard equipment.

SUMMARY

The disclosed embodiments relate to train control, specifically onboard Positive Train Control (PTC) equipment. Onboard PTC equipment is expensive and complex. The onboard segment of most widely used PTC system, Wabtec Corporation's I-ETMS® comprises: an onboard computer with a plurality of analog and digital inputs; an array of sensors throughout the locomotive measuring pressures, voltage, current, and track speed; eight radio receivers or transceivers in the GPS, Wi-Fi, cellular, and 220-MHz PTC data radio bands; an event recorder; a cab display; a penalty solenoid valve; an emergency solenoid valve; and power supplies. Practice among railroads has been to so equip every locomotive that operates as a controlling locomotive in a PTC territory. Locomotives often travel in coupled consists of two or more units, with a controlling locomotive in the leading position and one or more trailing units. Disclosed are embodiments of a system whereby a controlling (remote) locomotive, with a reduced complement of onboard PTC equipment, leverages the equipment in a fully disposed (host) trailing locomotive in a PTC territory. The reduced complement in the remote locomotive comprises principally a cab display and a penalty solenoid valve, both operatively connected to the onboard computer in the host locomotive. The many input signals required by PTC are available to the computer in the host, in valid form; they do not have to be duplicated in the remote locomotive. In the first embodiment, the operative connections between the remote and the host locomotives are direct-wired signal and data links. In another embodiment, the signals and data in the remote locomotive are aggregated into a remote terminal and communicated to the onboard computer through an aggregated link. Another embodiment pertains to push-pull passenger trains where an unpowered cab car is disposed in the same manner as a remote locomotive. Disclosed are variations of the basic principle where a locomotives with failed or non-interoperable PTC equipment can be adapted to operate as controlling locomotives in a PTC territory. All embodiments of the system retain the essential enforcement functions of PTC: when a hazard is detected on the track ahead, the system initiates a penalty or emergency application of the train brakes and removes all traction power. 

I claim:
 1. A system for leveraging onboard positive train control equipment in a consist of at least two locomotives, said system comprising: a) a multiple unit trainline that operatively connects all locomotives in said consist to coordinate the application of power, the application of dynamic braking, and the direction of movement; b) a full complement of onboard positive train control equipment installed within a host locomotive in a trailing position in the consist, said full complement comprising at least: i) an onboard computer configured to enforce train movement by selectively initiating a penalty application or an emergency application of the train brakes, and ii) an emergency solenoid valve that initiates said emergency application, upon actuation by said onboard computer, and iii) at least one GPS receiver and GPS antenna that provides precise geo-location data, corrected within said onboard computer for the distance from the antenna to the front coupler of the leading locomotive of said consist; and c) a reduced complement of onboard positive train control equipment installed within a remote locomotive in the leading position of the consist and configured as the controlling locomotive of the consist, said reduced complement comprising: i) an interactive cab display, operatively connected to said onboard computer in said host locomotive through a cab display data link, and ii) a penalty solenoid valve that said onboard computer in said host locomotive actuates through a penalty signal link, whereby an automatic brake valve in said remote locomotive responds to actuation of said penalty solenoid valve by making a penalty application of the train brakes, and whereby a group of operating controls, including a pneumatic control switch, upon detecting either a penalty application or an emergency application of the train brakes, cancels throttle and generator field signals imposed on said multiple unit trainline, thereby causing all engines in said consist to drop to idle speed and all traction power to be removed.
 2. The system in claim 1 further comprising: a) a first auxiliary signal link that communicates the state of said pneumatic control switch in said remote locomotive to said onboard computer in said host locomotive; b) a pressure switch in said remote locomotive that indicates whether said automatic brake valve in said remote locomotive is configured for operation in a leading position or a trailing position; and c) a second auxiliary signal link that communicates the state of said pressure switch to said onboard computer in said host locomotive.
 3. The system in claim 1, wherein: a) said cab display data link between said interactive cab display in said remote locomotive and said onboard computer in said host locomotive is a data cable; and b) said penalty data link between said penalty solenoid valve in said remote locomotive and said onboard computer in said host locomotive is a signal cable with at least two conductors, where spare conductors of the trainline may comprise a part of their length.
 4. The system in claim 1, wherein said cab display data link and said penalty signal link are aggregated within said remote locomotive by a remote terminal, and are thence communicatively coupled with said onboard computer in said host locomotive through an aggregated data link.
 5. A system for leveraging onboard positive train control equipment in a push-pull passenger train comprising a locomotive at one end and a cab car at the other end, such that the train may operate in both directions, said system comprising: a) a multiple unit trainline that operatively connects said cab car and said locomotive, such that said cab car, while in the leading position of the train, controls said locomotive in the application of power, the application of dynamic braking, and the direction of movement; b) a full complement of onboard positive train control equipment installed within said locomotive, said full complement comprising at least: i) an onboard computer configured to enforce train movement by selectively initiating a penalty application or an emergency application of the train brakes, and ii) an emergency solenoid valve that initiates said emergency application, upon actuation by said onboard computer, and iii) at least one GPS receiver and GPS antenna that provides precise geo-location data, corrected within said onboard computer for the distance from the antenna to the front coupler of the leading vehicle of said push-pull passenger train; and c) a reduced complement of onboard positive train control equipment installed within said cab car, which may be operated as the controlling vehicle of the train, said reduced complement comprising: i) an interactive cab display, operatively connected to said onboard computer in said locomotive through a cab display data link, and ii) a penalty solenoid valve that said onboard computer in said locomotive that actuates through a penalty signal link, whereby an automatic brake valve in said cab car responds to actuation of said penalty solenoid valve by making a penalty application of the train brakes, and whereby a group of operating controls, including a pneumatic control switch, upon detecting either a penalty application or an emergency application of the train brakes, cancels throttle and generator field signals imposed on said multiple unit trainline, thereby causing the engine in said locomotive to drop to idle speed and traction power to be removed.
 6. The system in claim 5 further comprising: a) a first auxiliary signal link that communicates the state of said pneumatic control switch in said cab car to said onboard computer in said locomotive; b) a pressure switch in said cab car that indicates whether said automatic brake valve in said cab car is configured for operation in a leading position or a trailing position; and c) a second auxiliary signal link that communicates the state of said pressure switch to said onboard computer in said locomotive.
 7. The system in claim 5, wherein: a) said cab display data link between said interactive cab display in said cab car and said onboard computer in said locomotive is a data cable; and b) said penalty data link between said penalty solenoid valve in said cab car and said onboard computer in said locomotive is a signal cable with at least two conductors, where spare conductors of the trainline may comprise a part of their length.
 8. The system in claim 5, wherein said cab display data link and said penalty signal link are aggregated within said cab car by a remote terminal, and are thence communicatively coupled with said onboard computer in said locomotive through an aggregated data link. 